f0138dfe17
* Moves code sections in tutorials to code files. * Removes wallet references. * Updates repo layout doc. * Removes remaining cordapp-tutorial references, replaced with cordapp-example. * Fixes broken link. * Misc docs fixes. * Refreshes the ServiceHub and rpc ops api pages. * Updates the cheat sheet. * Updates cookbooks. * Refreshes the running-a-notary tutorial. * Updates flow-testing tutorial * Updates tear-offs tutorial. * Refreshes integration-testing tutorial. * Updates to contract tutorial and accompanying code to bring inline with V1 release. * Refreshes contract-upgrade tutorial. * Fixed broken code sample in "writing a contract" and updated contracts dsl. * Added contract ref to java code. Fixed broken rst markup. * Updates transaction-building tutorial. * Updates the client-rpc and flow-state-machines tutorials. * Updates the oracles tutorial. * Amended country in X500 names from "UK" to "GB" * Update FlowCookbook.kt * Amended cheatsheet. Minor update on contract upgrades tutoraial. * Added `extraCordappPackagesToScan` to node driver. * Changes to match new function signature. * Update to reflect change in location of cash contract name.
2.4 KiB
Transaction tear-offs
Suppose we want to construct a transaction that includes commands
containing interest rate fix data as in oracles. Before sending the transaction to the oracle
to obtain its signature, we need to filter out every part of the
transaction except for the Fix commands.
To do so, we need to create a filtering function that specifies which fields of the transaction should be included. Each field will only be included if the filtering function returns true when the field is passed in as input.
../../docs/source/example-code/src/main/kotlin/net/corda/docs/tutorial/tearoffs/TutorialTearOffs.kt
We can now use our filtering function to construct a
FilteredTransaction:
../../docs/source/example-code/src/main/kotlin/net/corda/docs/tutorial/tearoffs/TutorialTearOffs.kt
In the Oracle example this step takes place in
RatesFixFlow by overriding the filtering
function. See filtering_ref.
FilteredTransaction holds filteredLeaves
(data that we wanted to reveal) and Merkle branch for them.
../../docs/source/example-code/src/main/kotlin/net/corda/docs/tutorial/tearoffs/TutorialTearOffs.kt
The following code snippet is taken from
NodeInterestRates.kt and implements a signing part of an
Oracle.
../../samples/irs-demo/src/main/kotlin/net/corda/irs/api/NodeInterestRates.kt
Note
The way the FilteredTransaction is constructed ensures
that after signing of the root hash it's impossible to add or remove
leaves. However, it can happen that having transaction with multiple
commands one party reveals only subset of them to the Oracle. As signing
is done now over the Merkle root hash, the service signs all commands of
given type, even though it didn't see all of them. This issue will be
handled after implementing partial signatures.